There is a new version of the 3-in-1 (the 3-in-1+) which is not yet supported by a number of menus. GBA ExpLoader is not compatible with the 3-in-1+. I thought the newest version of YSMenu was compatible with the 3-in-1+, but maybe not. Your only solution would be to wait for an update to GBA ExpLoader or YSMenu that is compatible with the 3-in-1+.